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Nx OsOperating system · Cisco

CVE-2017-12339

MEDIUM · 5.7 CVSS v3.0 Published 2017-11-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the CLI of Cisco NX-OS System Software could allow an authenticated, local attacker to perform a command injection attack. The vulnerability is due to insufficient input validation of command arguments to the CLI parser. An attacker could exploit this vulnerability by injecting crafted command arguments into a vulnerable CLI command. An exploit could allow the attacker to execute arbitrary commands at the user's privilege level. On products that support multiple virtual device contexts (VDCs), this vulnerability could allow the attacker to execute commands at the user's privilege level outside the user's environment. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode, Nexus 9000 Series Switches in standalone NX-OS mode, and Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCve99925, CSCvf15164, CSCvf15167, CSCvf15170, CSCvf15173.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A command injection vulnerability exists in the CLI parser of Cisco NX-OS System Software across multiple Nexus switch models. An authenticated local attacker can inject crafted command arguments through the CLI to execute arbitrary commands at the user's current privilege level due to insufficient input validation of command arguments.

MitigationApply the relevant Cisco software updates corresponding to bug IDs CSCve99925, CSCvf15164, CSCvf15167, CSCvf15170, and CSCvf15173. Until patched, restrict local CLI access to trusted administrative personnel only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nx OsOperating system
Affected:= 7.0\(0\)hsk\(0.357\)= 8.0\(1\)= 8.1\(0\)bd\(0.20\)
Lan Switch SoftwareOperating system
Affected:= 12.2\(1.107\)

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the NX-OS version
    Connect to the device CLI and run 'show version' to display the installed software version
    Affected if The displayed version matches 7.0(0)hsk(0.357), 8.0(1), or 8.1(0)bd(0.20)
  2. Identify the LAN Switch Software version
    Connect to the device CLI and run 'show version' to display the installed software version
    Affected if The displayed version matches 12.2(1.107)
  3. Confirm the product is in the affected family
    Verify the device model using 'show version' output - look for Nexus switches (Nexus 3000, 5000, 7000, 9000 series) or Catalyst switches running the affected software
    Affected if The device is a Cisco Nexus switch or Catalyst switch running NX-OS or LAN Switch Software at the affected versions
  4. Verify CLI access exists
    Confirm that local CLI authentication is configured and accessible - check with 'show running-config | include username' or similar authentication configuration
    Affected if Local CLI access is enabled for any user account, as the vulnerability can be exploited by any authenticated user

The environment is affected if the device runs Cisco NX-OS version 7.0(0)hsk(0.357), 8.0(1), or 8.1(0)bd(0.20), or Cisco LAN Switch Software version 12.2(1.107), and local CLI access is available to authenticated users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the relevant Cisco software updates corresponding to bug IDs CSCve99925, CSCvf15164, CSCvf15167, CSCvf15170, and CSCvf15173. Until patched, restrict local CLI access to trusted administrative personnel only.

Fix this in Nx Os Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-12339 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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